Abrasive sheet materials are widely used for a variety of applications and include, by way of illustration only, sandpapers, emery cloths, sanding discs for rotary sanders, and sanding strips for orbital and belt sanders. Abrasive sheet materials most often comprise a layer of an abrasive, i.e., abrasive particles or grit, which is attached to a substrate or base of varying thickness and basis weight by means of an adhesive. By utilizing very fine or super fine abrasive materials (less than 6 microns in average diameter), abrasive sheet materials also can be produced and used for fine sanding and polishing operations.
The reinforcement of paper by latex polymer impregnation (commonly referred to as latex saturation) is a long-established practice. The polymer employed typically is a synthetic material, most often a latex, and the paper may consist solely of cellulosic fibers or of a mixture of cellulosic and noncellulosic fibers. Polymer reinforcement may be employed to improve one or more of such properties as dimensional stability, resistance to chemical and environmental degradation, resistance to tearing, embossability, resiliency, conformability, moisture and vapor transmission, and abrasion resistance, among others.
Latex polymer barrier coatings may also be used to provide a smooth surface for the application of adhesive and abrasive particles. However, during the drying of latex polymer barrier coatings, small holes can appear in the latex layer. The holes appear due to the release of water vapor during drying and contraction of the dried film during curing. These holes are small, 10-30 microns in average diameter and are referred to as pinholes. Pinholes do not become a problem for fine size grit particles as used in the abrasive industry such as from grit 320 to 600 (35-16 microns in average size). However, in super fine grit applications, i.e., grit 800 to 1200 and finer (12 to 1.2 microns), the presence of pinholes affects the quality of the final abrasive paper product. For example, pinholes can allow super fine particles to become trapped or lodged in the holes. Such trapping of particles can result in a clump of abrasive particles on the final product surface. Such clumping creates an uneven surface that results in poor sanding quality.
Therefore, there exists a need in the art for a superfine abrasive paper backing that results in improved uniformity of grit particles on the surface thereof and a method of making thereof.